Table 6.
Chronotropic response to exercise measured during a single maximal cardiopulmonary exercise test in individuals with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), based on re-analysis of data from VanNess et al. (27).
| None (n = 20) | Mild (n = 67) | Moderate (n = 72) | Severe (n = 20) | |
|---|---|---|---|---|
| PEAK EXERTION (MEASURED HEART RATE) | ||||
| Predicted HR | 179 | 177 | 177 | 173 |
| Actual HR | 163 | 147 | 133 | 117 |
| % Predicted | 91.1 | 83.1 | 75.1 | 67.6 |
| 70% EXERTION (CALCULATED HEART RATE) | ||||
| Predicted HR | 126 | 124 | 124 | 121 |
| Actual HR | 114 | 102 | 93 | 82 |
| % Predicted | 90.4 | 82.3 | 75.0 | 67.8 |
(The authors used the Holmes criteria to identify ME/CFS). At both peak exertion and ventilatory anaerobic threshold, the difference between age-predicted heart rate and observed heart rate increased as American Medical Association metabolic impairment category worsened. HR, heart rate.